| 摘要 |
The mask (1) covers the face (5) and the neck (6) of the user and has holes which correspond to the eyes and mouth of the wearer. It is held against the face by straps (39,45) which pass round the head and by an elastic cord held in a tubular hem (7) around the edge of the mask. The mask has an outer layer (2) which is made from a material which is permeable to air and is hygroscopic and retains heat, such as knitted wool. An inner layer (29) is made from material which is hygroscopic, such as cotton flannel.
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